1. Field of the Invention
The present invention relates to a cabinet molded in resin for use with a cabinet of a television receiver, for example.
2. Description of the Related Art
FIG. 1 of the accompanying drawings shows a cabinet of a television receiver. As shown in FIG. 1, there is provided a television receiver 1 which includes a cathode ray tube (CRT) 2 disposed at the central portion of the front surface thereof as an image display portion and left and right grill portions 3 formed on a cabinet of the cathode ray tube 2. The grill portions 3 have a plurality of holes of very small diameter disposed close together in the vertical and horizontal directions. The left and right grill portions 3 have speaker devices 4 incorporated therein. Sounds reproduced from the speaker devices 4 are emanated to the outside of the cabinet through the holes defined on the left and right grill portions 3.
It is customary that a grill portion of a cabinet of a television receiver is composed of a cabinet molded in synthetic resin and a metal plate called punching net having very small holes attached to the cabinet or that a grill portion is composed of a cabinet molded in synthetic resin and a fiber material having a gas permeability, such as a SARAN (trade name of polyvinylidene chloride manufactured by Dow Chemical Co., Ltd.) net bonded to the cabinet. When however the grill portion is made of different materials as described above, it takes much time to manufacture cabinets of television receivers and television receivers become expensive.
To solve the above-mentioned problem, it is proposed to form a grill portion by using only a synthetic resin. According to this previously-proposed method, a grill portion having a plurality of holes of very small diameter disposed close together in the vertical and horizontal directions can be made by the same resin material which forms a cabinet.
FIG. 2 is a perspective view of an example of a grill portion 3 made of a synthetic resin and showing the grill portion 3 of the cabinet from the rear surface side.
As shown in FIG. 2, the grill portion 3 has a plurality of very small holes 5 (e.g., diameter of the hole 5 is about 1 mm) constructing the grill portion 3. These holes 5 are defined on the grill portion 3 close together in the vertical and horizontal directions. The grill portion 3 reduces its thickness at the portions of the holes 5 as compared with those of other portions thereof. Reinforcing ribs 6 are formed on the grill portion 3 at substantially equal spacing in order to reinforce the thin portions of the holes 5. Thicknesses of the portions of the reinforcing ribs 6 are formed are substantially the same as those of other portions of the grill portion 3 of the cabinet so that the portions of the reinforcing ribs 6 increase their thicknesses as compared with the portions of the holes 5. Therefore, the thin portions of the holes 5 can be reinforced.
The reinforcing ribs 6 function also as so-called flow leaders. The flow leaders support resin to properly flow when the cabinet is molded in resin. Specifically, since the reinforcing ribs 6 are disposed on the grill portion 3 with a proper interval, a resin material supplied from the side surface side of the cabinet along dashed arrows when the cabinet is molded in resin can be flowed through the portions of the reinforcing ribs 6 and filled up to the front surface side of the cabinet, thereby the cabinet being molded in resin satisfactorily.
If however the grill portion 3 is molded in synthetic resin, as shown in FIG. 2, there is then the disadvantage that opening portions 7 into which the resin for molding is not filled are produced on the portions of the holes 5 distant from the reinforcing ribs 6. Specifically, when the cabinet is molded in synthetic resin, the resin is mainly flowed in the grill portion 3 at its relatively thick portions of the reinforcing ribs 6 and the resin is difficult to be filled into the portions of the holes 5 distant from the reinforcing ribs 6,.causing the opening portions 7 to be produced easily. Therefore, it is difficult to mold the grill portion having a plurality of very small holes disposed close together to a resin molded assembly of relatively large size, such as the cabinet of the television receiver.
In order to eliminate the above-mentioned disadvantage, the number of the reinforcing ribs 6 has to be increased. Since however the holes 5 cannot be formed on the portions of the reinforcing ribs 6, if the number of the reinforcing ribs 6 is increased, then the opening area that is provided by the holes 5 is unavoidably reduced, disabling the grill portion 3 to function as the sound emanating portion of the speaker. Therefore, there is a limitation in increasing the number of the reinforcing ribs 6.